<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <script type="text/javascript" src="../script/jquery-3.6.0.min.js"></script>
  <script type="text/javascript">
    window.onload = function (){
      var username = document.getElementById("username");
      alert("username value= " + username.value);

      var $username = $(username);
      alert("username value= " + $username.val());
    }
  </script>
</head>
<body>
用户名 <input type="text" id="username" name="username" value="韩顺平教育"/>
</body>
</html>
